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Table 1 Baseline characteristics of all participants

From: Increased frequency of intermetatarsal and submetatarsal bursitis in early rheumatoid arthritis: a large case-controlled MRI study

  RA Other arthritides1 P value, RA vs other arthritides Healthy controls P value, RA vs healthy controls
n = 157 n = 284   n = 193  
Clinical features
 Age, mean (SD) 59 (14) 56 (17) 0.07 50 (16) < 0.001
 Female, n (%) 109 (69) 158 (56) 0.005 136 (71) 0.83
 BMI, mean (SD) 26 (5) 27 (4) 0.52 25 (4) 0.003
Symptom duration, in weeks, median (IQR) 10 (5–28) 8 (4–26) 0.13 NA NA
Swollen joint count, median (IQR) 7 (2–11) 2 (1–4) < 0.001 NA NA
CRP, mg/L, median (IQR) 9 (4–26) 6 (3–16) < 0.001 NA NA
RF positive, n (%) 106 (68) 51 (18) < 0.001 NA NA
ACPA positive, n (%) 87 (59) 69 (25) < 0.001 NA NA
MRI features
 Mean number of lesions per patient, n (SD)
  Intermetatarsal bursitis 1.6 (1.4) 0.6 (1.0) < 0.001 0.2 (0.7) < 0.001
  Submetatarsal bursitis 0.4 (0.8) 0.07 (0.3) < 0.001 0.04 (0.2) < 0.001
  Morton’s neuroma 0.4 (0.6) 0.06 (0.3) < 0.001 0.03 (0.2) < 0.001
  Diffuse submetatarsal alterations 0.5 (1.1) 0.3 (0.9) 0.068 0.3 (0.9) 0.092
  1. RA rheumatoid arthritis, SD standard deviation, BMI body mass index, IQR interquartile range, CRP C-reactive protein, RF rheumatoid factor, ACPA anti-citrullinated peptide antigen (anti-CCP), MRI magnetic resonance imaging, NA not applicable
  2. 1This group included the following diagnoses: unclassified arthritis (n = 148), psoriatic arthritis or spondyloarthritis (n = 45), inflammatory osteoarthritis (n = 23), reactive arthritis (n = 7), crystal arthropathy (n = 21), remitting seronegative symmetrical synovitis with pitting edema (n = 12), and other diagnoses (n = 28)